“暴风雪”航天飞机将再战江湖

1988年11月,前苏联成功发射了“暴风雪”航天飞机,打破了美国独家运营航天飞机的垄断局面。前苏联解体后,由于俄罗斯经济的不景气,“暴风雪”一直被封存着。随着国际空间站建造进度加快、国际商用卫星发射市场的繁荣和太空旅游热潮的兴起,俄航天有关部门正考虑让“暴风雪”再次复出     

出入太空的"雄鹰"写在航天飞机第101次发射之际

航天飞机是把航天与航空技术有机结合的创举。１９８１年，世界上第一架航天飞机，美国的“哥伦比亚”号进行处女航行，到去年 １１月，美国航天飞机进行了第１０１次航行。近几次航天飞机发射给国际空间站运送了航天员与所需物资。目前美国还在研究新一代航天飞机     

Shuttle performance improvements through multiple database integration

The ability to model and analyze system performance is a key enabler when you are extending the operational life of complex systems. This is especially true when the system is operating in a hostile environment, such as space. This paper discusses a change made to the Space Shuttle main engines (SSMES) that affected the solid rocket booster (SRB) performance, and illustrates how databases maintained by the different subsystem contractors can be integrated, correlated, and evaluated to improve a subsystem component performance model. The enhanced model can be used not only for better prediction of component performance on the existing system, but can be used on upgrades to the system, or the next generation space shuttle solid rocket. motor.     

航天飞机自动着陆轨迹优化设计

采用沿约束轨迹的推演计算方法及优化原理对航天飞机自动着陆飞行轨迹进行优化设计。首先根据过载、垂直下降率、连续性和平稳性要求确定飞行轨迹的基本形状，然后采用两点边值优化方法对轨迹参数进行优化设计以获得理想的接地动压。与传统的和制导系统联系在一起的轨迹设计方法相比，该方法具有简便、快速、可重复使用、鲁棒性强等特点。     

空天飞机用涡轮风扇-冲压组会发动机的设计研究

本文对分离式涡扇-冲压发动机进行了初步设计研究,讨论了如何选择发动机结构外形,设计参数(包括旁路比、压力比、涡轮前温度和燃料种类)以及涡轮冲压发动机工作方式等。通过计算表示了不同设计参数对发动机性能的影响,还分析了普通进气道对发动机性能的影响。     

High rate data link front end design and performance during AlphaMagnetic Spectrometer Space Shuttle flight, May 1998

In June 1998, Metsahovi Radio Observatory participated in a 10-day shuttle mission, STS-91, ground support activity by receiving, archiving, and making available, the so-called High Rate Data (HRD) from Alpha Magnetic Spectrometer (AMS). The goal of this particle physics experiment project was to detect antimatter in space. Some aspects of the HRD link performance are discussed     

航天飞机末端区域能量管理段制导技术概述

末端区域能量管理段主要是控制航天飞机的动能和势能．使航天飞机最终达到进场着陆段的初始要求，以保证其最终成功着陆。在最终制导系统引入一个能量基准剖面，通过调整飞行距离、动压或速度制动使航天飞机达到标准的能量状态。将末端区域能量管理段划分为四个飞行段，并对这四个飞行段的基本设计思想、制导技术及过程进行了研究。经过实际的航天飞机飞行验证．证明这种方案具有良好的制导效果。     

航天飞机三维最优再入轨道及气动加热过程

本文应用现代控制理论研究了航天飞行器三维最优再入轨道和与轨道参数密切相关的气动加热过程。文中选择飞行器迎角和倾斜角作为控制变量,以飞行器气动加热率和飞行过载沿轨道积分最小作为优化性能指标,按极大原理导出最优再入轨道有约束控制的非线性两点边值问题。采用了数值优化方法——共轭梯度法求解有升力飞行器的最优再入轨道及其热过程。文中以允许误差法讨论了权系数和罚函数的选取方法;对不同速度范围研究了不同的加热模型;按热平衡方程与优化轨道同步迭代的方法求得了算例数值结果。算例的数值结果与文献[13]的量值是一致的。     

Intersatellite communications optoelectronics research at theGoddard Space Flight Center

A review is presented of current optoelectronics research and development at the NASA Goddard Space Flight Center for high-power, high-bandwidth laser transmitters; high-bandwidth, high-sensitivity optical receivers; pointing, acquisition, and tracking components; and experimental and theoretical system modeling at the NASA Goddard Space Flight Center. Program hardware and space flight opportunities are presented     

航天飞机防热结构温度场的数值计算研究

本文采用有限差分法及有限元素法计算了航天飞机防热结构的一、二维温度分布,并与飞行实测数据及实验结果进行了比较,符合较好。     

Performance evaluation of digital beamforming strategies for satellite communications

Smart antennas are becoming one of the promising technologies to meet the rapidly increasing demands for more capacity of satellite communication systems. A main component in a smart antenna system is beamforming. Because of the limitations of analog beamforming, digital beamforming will be employed in future satellite communication systems. We evaluate the performance of various digital beamforming strategies proposed in the literature for satellite communications: 1) single fixed beam/single user, 2) single fixed beam/multiple users, 3) single adaptive beam/single user, and 4) single Chebyshev dynamic beam/multiple users. Multiple criteria including coverage, system capacity, signal-to-interference-plus-noise ratio (SINR), and computation complexity are used to evaluate these satellite communication beamforming strategies. In particular, a Ka-band satellite communication system is used to address the various issues of these beamforming strategies. For the adaptive beamforming approach, subarray structure is used to obtain the weights of a large 2D antenna array, and a globally convergent recurrent neural network (RNN) is proposed to realize the adaptive beamforming algorithm in parallel. The new subarray-based neural beamforming algorithm can reduce the computation complexity greatly, and is more effective than the conventional least mean square (LMS) beamforming approach. It is shown that the single adaptive beam/single user approach has the highest system capacity.     

"成渝空中快巴"点燃支线航空新亮点

近几年我国支线航空的发展由“热火朝天”回落到“悄无声息”,在潮起潮落中品味着市场的冷暖,也酝酿着新的变革。去年9月28日,四对航空公司在沉寂多年的成都—重庆航线上开通“穿梭空中快速巴士”,获得了令人惊喜的成功,成为国内支线航空暗淡天空中的新亮点。这一事件不仅引发了成渝客运市场的重新洗牌,更为发展中国支线航空事业带来了崭新的启示